Modeling pronunciation variation for spontaneous speech synthesis

Integration of pronunciation modeling into speech synthesis makes synthetic speech more natural and colloquial. Pronunciation variation as one observable effect in spontaneous speech is a step towards spontaneous speech synthesis. In the previous works (see Proc. ICASSP, vol.1, p.417-20, Orlando, FL, USA, 2002 and Proc. ICASSP, Hong Kong, PR China, Apr. 2003) we introduced different duration control methods in speech synthesis. These methods are based on the observation that words, which are very likely to occur in a given context are pronounced faster and less accurately than improbable ones (see D. Jurafsky et al., Proc. ICASSP, vol.2, p.801-4, Salt Lake City, USA, 2001). Therefore we use the probability of a word in its context to either control directly the local speaking rate, or to select appropriate pronunciation variants in order to change the local speaking rate. Extending these methods by a pronunciation sequence model, we involve knowledge about how well two subsequent variants fit together. Using this proposed algorithm we could further improve the natural and colloquial listening impressions.